Gibbon

Gibbons (an arboreal ape species) are easy to hear but notoriously difficult to film. Camerawoman Justine Evans climbed a tree, built a platform, and spent several days waiting until she finally captured the acrobatic creatures swinging through the canopy.

Gibbons can swing up to 50 feet at a time at speeds up to 35 mph and at heights up to 200 feet above the ground. Gibbon families "sing" when protecting their territory and their voices can be heard up to two miles away. This is how scientists — and poachers — locate them.

Gibbons are threatened primarily by the loss of their forest habitat, but the illegal wildlife trade, the use of their body parts in traditional medicines and poaching also contribute.